tag:theconversation.com,2011:/ca/topics/malaria-elimination-22210/articlesmalaria elimination – The Conversation2017-12-14T17:39:20Ztag:theconversation.com,2011:article/875302017-12-14T17:39:20Z2017-12-14T17:39:20ZPeople stay vigilant to the threat of malaria, even when infections fall<figure><img src="https://images.theconversation.com/files/198118/original/file-20171207-28921-i5c6y8.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Karen Kasmauski/MCSP)</span></span></figcaption></figure><p>Since the turn of the century great strides have been made to reduce the burden of malaria in sub-Saharan Africa. But the disease, spread by the Anopheles mosquito, still remains a major threat: in 2015 there were an estimated 212 million cases worldwide, according to the most recent <a href="http://www.who.int/malaria/publications/world-malaria-report-2016/report/en/">World Malaria Report</a>. </p>
<p>Malaria can be prevented in several ways, in particular by sleeping under an insecticide-treated bed net and spraying homes with an insecticide. </p>
<p>Bed nets are a commonly used prevention method while indoor residual spraying is only done in specific high risk areas. In 2015, about 53% of the at-risk population in sub-Saharan Africa <a href="http://www.who.int/malaria/publications/world-malaria-report-2016/report/en/">slept under an insecticide treated net</a>. In the same period, 3.1% of the population at risk of contracting malaria in the region had their homes protected. </p>
<p>Bed nets are distributed through mass campaigns and at antenatal and child vaccination clinics. But of course people can decide not to use the nets, even if they receive one. Indoor residual spraying on the other hand is a public intervention carried out by national governments with the help of international organisations. </p>
<p><a href="https://hal-pjse.archives-ouvertes.fr/halshs-00911364/document">Our study</a> explores the effect of malaria risk in the area and of indoor residual spraying on individual decision to use bed nets. We focus on nine countries in sub-Saharan Africa in which malaria is endemic: Angola, Burundi, Cameroon, Liberia, Madagascar, Malawi, Mozambique, Tanzania and Uganda. Our data combines information on household behaviours and characteristics from <a href="http://dhsprogram.com/">the Demographic and Health Survey data</a> with information on malaria prevalence from <a href="http://www.map.ox.ac.uk/">the Malaria Atlas Project</a>.</p>
<h2>An eradication plan</h2>
<p>The World Health Organisation has set an ambitious goal of controlling and eradicating the disease by 2030. This includes reducing malaria cases and mortality rates by at least 90% and eliminating malaria in at least 35 countries by 2030.</p>
<p>But for eradication campaigns to be successful the relationships between malaria prevalence, indoor residual spraying and individual bed net usage are crucial. </p>
<p>Numerous studies have evaluated the effectiveness of bed nets and indoor residual spraying as malaria prevention interventions. </p>
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<img alt="" src="https://images.theconversation.com/files/198123/original/file-20171207-28958-nth8cd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip">
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<span class="caption">A worker prepares a canister for internal residual spraying to prevent malaria in a high risk area in Ethiopia.</span>
<span class="attribution"><span class="source">flickr/USAID</span></span>
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<p>But there are two points that may have been overlooked. The first is whether the risk of getting malaria – malaria prevalence in the area – has any effect on individual bed net usage. The second is whether bed nets are used in houses that are covered by an indoor residual spraying programme. </p>
<p>Our study investigates these two questions. Firstly, we ask whether the risk of being infected in an area influences people to use their bed nets. When the prevalence of the disease decreases in the area, does bed net usage decrease proportionally or more than proportionally? </p>
<p>Secondly, we investigate what effect spraying has on people using the nets: do people substitute the nets with spraying? Does a publicly provided intervention reduce the likelihood of people using the nets?</p>
<p>In most regions, bed nets are the main tool in the fight against malaria. If people are using bed nets less because they no longer see malaria as a threat, eradicating the disease may become impossible.</p>
<p>Our results show that as malaria prevalence falls, people reduce their bed net usage. Spraying does not reduce the proportion of people who chose to use a bed net. In fact, spraying increases the use of bed nets. </p>
<h2>A clear message</h2>
<p>One possible explanation for the increased use is that as governments and organisations go through houses spraying the insecticide, the households receive the message – either explicitly or implicitly – that malaria is a real threat and that one should do what they can to prevent it.</p>
<p>Individual responses to malaria risk and spraying programmes mean that international efforts to control the disease will not be hampered, as is feared. And it means that the global health community can continue its quest to eradicate malaria in the next 13 years.</p><img src="https://counter.theconversation.com/content/87530/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gabriel Picone receives funding from the Fogarty International Center for this project.</span></em></p><p class="fine-print"><em><span>Bénédicte Apouey received funding from the Fogarty International Center -- a branch of the United States government&#39;s National Institutes of Health -- for this project.</span></em></p><p class="fine-print"><em><span>Robyn Kibler does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>When there are two malaria prevention interventions available people don't take an either or approach -- they consider that the two interventions are complementary.Gabriel Picone, Professor in the Department of Economics, University of South FloridaBénédicte Apouey, Chercheuse en sciences sociales au CNRS, Paris School of Economics – École d'économie de ParisRobyn Kibler, Postdoctoral Researcher, University of South FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/863552017-11-22T12:17:49Z2017-11-22T12:17:49ZHow drones are being used in Zanzibar's fight against malaria<figure><img src="https://images.theconversation.com/files/195789/original/file-20171122-6013-yq6uu8.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">Makame Makame from the Zanzibar Malaria Elimination Programme holds one of the drones used to map malaria vectors.</span> <span class="attribution"><span class="source">Andy Hardy</span></span></figcaption></figure><p>On a typically hot and humid July day in Stonetown, the capital of Zanzibar, a gaggle of children, teenagers and the odd parents watched our small drone take flight. My colleagues Makame Makame, Khamis Haji and I had finally found the perfect launch spot.</p>
<p>With a high-pitched humming, the drone took to the air. It sounded like a big mosquito – appropriate, since we were testing the use of drones for mapping aquatic malaria habitats. These shallow sunlit water bodies teem with mosquito larvae. In a matter of days, the larvae will emerge as adult mosquitoes in search of a blood meal. If one of those mosquitoes bites a human infected with malaria, it will become a vector for the disease and continue its deadly transmission cycle.</p>
<p>Zanzibar is a Tanzanian archipelago off the coast of East Africa. Both it and mainland Tanzania have fought a long, well documented battle with malaria. <a href="http://www.who.int/gho/malaria/epidemic/deaths/en/">Globally</a>, the disease infects over 200 million people annually and is responsible for killing approximately 500,000 people each year.</p>
<p>The <a href="http://www.who.int/topics/millennium_development_goals/diseases/en/">Millennium Development Goals</a> prompted a number of large scale campaigns across sub-Saharan Africa to combat malaria. <a href="https://www.cdc.gov/malaria/malaria_worldwide/reduction/itn.html">Millions of bed nets</a> were distributed. Insecticide was supplied to spray in homes across communities. The aim was to stop people getting bitten, interrupting the transmission cycle. </p>
<p>It’s been a real success story, leading to a notable decrease in the disease’s prevalence. Some areas of Zanzibar have seen <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3639098/">prevalence levels drop</a> from 40% of the population having malaria to less than 1%.</p>
<p>Now epidemiologists and public health managers are looking to complement indoor-based nets and spraying with outdoor based solutions. In effect, they’re taking the battle to mosquitoes. And drones are a crucial part of their armoury. One of the main challenges to disease managers is finding small water bodies that mosquitoes use to breed. This is where drones come in – for the first time, drone imagery can be captured over large areas which can be used to create precise and accurate maps of potential habitats.</p>
<h2>Tracking mosquitoes</h2>
<p>We <a href="https://www.cdc.gov/malaria/about/biology/mosquitoes/">know</a> that once an adult mosquito has fed and rested, it will typically go in search of a mate. Then it moves on to a suitable location – an aquatic habitat like the fringes of river channels, roadside culverts and irrigated rice paddies – to lay its eggs.</p>
<p>Public health authorities need to be able to locate and map these water bodies so they can be treated using a larvicide like DDT. This process is known as larval source management, and was successfully used in Brazil and Italy many decades ago. There, the DDT killed mosquito larvae – but could also be <a href="http://www.sciencedirect.com/science/article/pii/S0169475899016051">devastating</a> for local ecology as well as having adverse effects on human health.</p>
<p>Today much safer, low toxicity replacements have been developed. The problem is that they come at a cost. Resources are also needed to disseminate the larvicide and to locate the water bodies that host the mosquito eggs and larvae. Some of these hideaways are tough to find on foot, and if water bodies are accurately mapped a larvicide campaign could end up being a waste of time.</p>
<p>My institution, <a href="https://www.aber.ac.uk/en/dges/staff-profiles/listing/profile/ajh13">Aberystwyth University</a> in Wales, is working with the Zanzibar Malaria Elimination Programme to fly drones over known malaria hot spots. </p>
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<a href="https://images.theconversation.com/files/192794/original/file-20171101-19858-1muno94.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img alt="" src="https://images.theconversation.com/files/192794/original/file-20171101-19858-1muno94.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip"></a>
<figcaption>
<span class="caption">A rice paddy in Mwera, Zanzibar. These and other watery sites are perfect spots for mosquitoes to lay their eggs.</span>
<span class="attribution"><span class="source">Image collected by Andy Hardy using a DJI Phantom 3 drone.</span></span>
</figcaption>
</figure>
<p>In 20 minutes, a single drone is able to survey a 30 hectare rice paddy. This imagery can be processed and analysed on the same afternoon to locate and map water bodies. This has proved to be highly accurate and efficient. This is all using one of the most popular off-the-shelf drones, the Phantom 3 made by DJI. These are about the size of a shoebox, weighing a little more than a bag of sugar (1.2 kg) and are used throughout the world for both leisure and commercial photography.</p>
<p>We started off working in test locations across Zanzibar but now, with the support of the <a href="http://www.ivcc.com/">Innovative Vector Control Consortium</a> – a non-for-profit partnership aiming to create novel solutions for preventing disease transmission – we’re widening our range to explore how this technology can be incorporated into operational malaria eliminating activities.</p>
<p>It doesn’t stop there. We plan to incorporate the drone imagery into smartphone technology to help guide larvicide spraying teams to water bodies on the ground, and to track their progress and coverage. There’s also an exciting drive towards automatically disseminating larvicide from the drones themselves.</p>
<h2>Getting people involved</h2>
<p>Despite these exciting advances, operators need to be mindful of the negative side of drones: invasion of privacy; collisions with aircraft and birdlife; their association with warfare. These are very real concerns for the public.</p>
<p>In Zanzibar, we worked alongside village elders to show them the drones and explain exactly what we plan to use them for. We also encouraged people to gather around when we were looking at live-feed footage from the drone’s onboard camera. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/-pkmgpcNXFg?wmode=transparent&amp;start=59" frameborder="0" allowfullscreen></iframe>
<figcaption><span class="caption">Collation of drone imagery recorded using a DJI Phantom 3 over a range of sites across Zanzibar.</span></figcaption>
</figure>
<p>This introduced people to our work and gave them a chance to see how drones and similar technologies, used alongside traditional indoor-based interventions, can really help to make malaria elimination in their community a reality.</p><img src="https://counter.theconversation.com/content/86355/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andy Hardy receives funding from the UK Natural Environment Research Council, the UK Space Agency and the Innovative Vector Control Consortium. </span></em></p>Epidemiologists and public health managers are looking to complement indoor-based malaria solutions with those that focus on the outdoors. Drones are a crucial part of their armoury.Andy Hardy, Lecturer in Remote Sensing and GIS, Aberystwyth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/870202017-11-14T13:27:52Z2017-11-14T13:27:52ZSouthern Africa is slipping again after coming close to eliminating malaria<figure><img src="https://images.theconversation.com/files/194542/original/file-20171114-27625-6lfukr.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Brant Stewart/RTI</span></span></figcaption></figure><p><em>In the last five years, South Africa, Botswana, Namibia and Swaziland have all been on the verge of eliminating malaria. In fact, progress had been so good that the southern African region had been tipped to be malaria free by 2018. But a spike in cases this year means that it’s unlikely to meet the target. A new target has been set for 2020. The Conversation Africa’s Health and Medicine editor Candice Bailey asked Professor Rajendra Maharaj to explain why.</em></p>
<p><strong>Why has there been a spike in malaria cases in southern Africa? Is it unusual?</strong></p>
<p>Over the last few years there has been a downward trend in the number of malaria cases globally. There was a <a href="https://theconversation.com/parts-of-southern-africa-are-within-tantalising-reach-of-eliminating-malaria-49848">marked decrease in cases</a> in South Africa and in several other countries in the region including Swaziland, Botswana and Namibia. This trend was so encouraging that the region had become comfortable with the idea that it would reach the target of eliminating malaria by 2018. South Africa, for example, experienced a serious epidemic in the 1999/2000 malaria season where over 62 000 cases were recorded but with reinforced interventions, the cases decreased to under 5 000 in 2016.</p>
<p>The countries in the region achieved this by implementing evidence-based indoor residual programmes and improving diagnostics and treatment, introducing artemisinin-based combination therapy.</p>
<p>But this year <a href="http://www.nicd.ac.za/index.php/update-malaria/">figures</a> in some parts of South Africa were triple what they were last year. The reality is that in only some parts of the country will we have eliminated malaria. Although the number of cases reported from KwaZulu-Natal increased, it’s still possible to reach the 2020 goal but the same can’t be said for Mpumalanga and Limpopo. These two areas receive many imported cases from Mozambique and Zimbabwe. </p>
<p>This spike is not restricted to South Africa. It has happened in all <a href="http://www.nicd.ac.za/index.php/malaria-advisory-april-2017/">southern African countries</a>. But the increase has been the greatest in Namibia and Swaziland.</p>
<p>We have yet to confirm what caused the spike in the region. We know that the mild winter conditions created fertile ground for mosquito breeding. But we still need to understand what’s behind the increase in cases so that we can tackle the problem. </p>
<p>There are many questions. For example, was there a failure in the case management? Was there a relaxed attitude to implementing all the planned interventions? We still need to answer these questions. There are several possible reasons for the spike.</p>
<p>One possibility is the sub-optimal insecticide spray coverage contributed to the increased transmission. Another is the Malaria Control Programme was ill prepared for the epidemic. At one point this year there was as shortage of drugs in the province and these had to brought in as a matter of urgency after the epidemic struck. </p>
<p>A third possibility is that with heavy rains preceding a very dry period, there were many suitable pools for breeding and the hot conditions were ideal for mosquito breeding.</p>
<p><strong>How does the region handle malaria control currently. Are there weaknesses in the strategy?</strong></p>
<p>To control malaria, countries in the region use one of two strategies: <a href="http://apps.who.int/iris/bitstream/10665/177242/1/9789241508940_eng.pdf?ua=1&amp;ua=1">indoor residual spraying</a> (IRS) and the use of <a href="http://www.who.int/mediacentre/factsheets/fs094/en/">Long-lasting Insecticide Treated Nets</a> (LLINs). These are either used in isolation or as part of an integrated programme. South Africa uses indoor residual spraying and little larval control measures that targets the breeding sites of mosquitoes. In Swaziland, Botswana and Namibia the focus has been on indoor spraying but net coverage has achieved high levels in these countries. </p>
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<p>The World Health Organisation <a href="http://www.who.int/heli/risks/vectors/malariacontrol/en/index6.html">recommends</a> the use of integrated mosquito control where more than one method is used.</p>
<p><strong>What are the other challenges in controlling malaria in the region? And why does the focus need to change?</strong></p>
<p>The region’s most powerful and effective vector control strategy has been spraying houses with the powerful insecticide DDT through the indoor residual spraying. But the impact of indoor residual spraying is often diluted due of <a href="http://www.who.int/malaria/publications/atoz/insecticide-resistance-implications/en/">insecticide resistance</a> to the currently used insecticides. Insecticides should be used on a rotational basis or in a mosaic spray pattern to mitigate resistance developing.</p>
<p>In areas where there’s been high levels of transmission, it was found that the spray coverage for insecticides recommended by the World Health Organisation wasn’t optimal. It’s <a href="http://apps.who.int/iris/bitstream/10665/177242/1/9789241508940_eng.pdf?ua=1&amp;ua=1">recommendation</a> is that 80% of the houses in a malaria infected community should be sprayed. But the region is not achieving this coverage.</p>
<p>Another cause for concern is that there are an increasing number of people refusing to have their homes sprayed with insecticide. This may be due to a lack of awareness of the need to have the houses sprayed. The reasons for this are unclear, but its suspected to be linked to the disease burden being low. </p>
<p>Participating in the indoor residual spraying programme is purely voluntary. People can’t be forced to have their homes sprayed as there is no legislation in place to compel them to have their houses sprayed. If people refuse, there’s nothing that can be done except to educate the homeowner to gain permission to spray. </p>
<p><a href="http://www.who.int/heli/risks/vectors/malariacontrol/en/index6.html">DDT</a> is the cheapest insecticide. It has a long residual life on the market and as a result countries with limited resources use it as a tool to control vectors. There is very little resistance to DDT in the region but there is enormous political pressure to move away from using DDT.
What is needed in these countries are robust public awareness campaigns informing people that, even when there have the is no disease, malaria can resurge as long as there are vector mosquitoes in the area. </p>
<p>There is evidence from developing countries in other parts of the world that elimination can be achieved. Sri Lanka is the latest country to <a href="http://www.searo.who.int/mediacentre/releases/2016/1631/en/">achieve elimination</a>. They had a very strong vector control programme that succeeded in reducing the caseload significantly. Once this was achieved proper case management further reduced the case numbers. </p>
<p>And when there were no local cases an intensive surveillance programme was implemented. Although elimination was achieved, entomological surveillance and disease surveillance was strengthened.</p><img src="https://counter.theconversation.com/content/87020/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rajendra Maharaj does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A spike in the number of malaria cases in southern Africa means that the region will not meet its initial target of eliminating malaria by 2018.Rajendra Maharaj, Unit Director of the Office of Malaria Research , South African Medical Research CouncilLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/765262017-04-24T15:59:28Z2017-04-24T15:59:28ZWhat Africa still needs to do to eliminate malaria<figure><img src="https://images.theconversation.com/files/166535/original/file-20170424-12658-wbnpmz.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">A young girl with malaria rests in the inpatient ward of a health centre in the South Sudan. </span> <span class="attribution"><span class="source">Reuters/Adriane Ohanesian </span></span></figcaption></figure><p>Malaria is one of the oldest and <a href="http://www.planet-science.com/categories/over-11s/human-body/2012/03/malaria---the-deadliest-parasitic-disease-on-the-planet.aspx">deadliest</a> infectious diseases affecting man. It is an ancient and modern disease – descriptions of illnesses similar to malaria are found in <a href="http://www.sciencedirect.com/science/article/pii/S0020751916301229">ancient texts</a> from China, India, the Middle East, Africa and Europe. </p>
<p>Malaria parasites have <a href="http://www.sciencedirect.com/science/article/pii/S0020751916301229">co-evolved</a> – which involves genetic changes and adaptation – with people as their hosts over a period of four thousand years. </p>
<p>After the Second World War, the <a href="http://www.who.int/bulletin/volumes/86/2/07-050633/en/">Global Malaria Eradication Programme</a> was intensified by the discovery of <a href="https://www.aei.org/publication/the-rise-fall-rise-and-imminent-fall-of-ddt/">DDT</a>, a powerful pesticide. The campaign partially reduced the malaria transmission cycle and infection rates within a short time.</p>
<p>The US eradicated malaria by <a href="http://www.the-scientist.com/?articles.view/articleNo/29069/title/US-Malaria-Deaths--1870/">1951</a> but in <a href="http://www.isid.ac.in/%7Etridip/Teaching/DevelopmentMicroeconomics/Spring2012/Readings/03Health/07Bleakley-AEJAE2010.pdf">Latin and South America</a> pockets recurred two decades later. </p>
<p>Today malaria has been eliminated in <a href="http://www.who.int/malaria/areas/elimination/overview/en/">26 other countries</a> including Cuba, Italy and Japan. About 65 countries are planning to eradicate the disease between 2020 and 2030.</p>
<p>Africa carries a disproportionately high burden of malaria cases. In 2015 <a href="http://apps.who.int/iris/bitstream/10665/252038/1/9789241511711-eng.pdf?ua=1">214 million</a> people across the world were infected with malaria leading to about 430 000 deaths. Of these, 90% occurred in Africa. And two countries on the continent, Nigeria and the Democratic Republic of Congo, accounted for more than 35% of global malaria deaths.</p>
<p>There has been some improvement. Between 2010 and 2015 there was a 21% reduction of malaria cases reported on the continent, and a 31% reduction in number of deaths. </p>
<p>But Africa needs to urgently put a number of additional measures in place to speed up these advances, and to move towards eliminating the disease. These include accelerated investment and deployment of vaccines, new diagnostic tools, new funding strategies for malaria control and keeping in check the drug and insecticide resistance challenge.</p>
<p>Funding is also key if African countries are going to move closer to eradication. Evidence shows that eliminating malaria in Africa has been weakened by the <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-016-1171-3">lack of sustained funds</a>. </p>
<h2>What’s made a difference, where the problems lie</h2>
<p>The following major investments in the last one and a half decades have led to the incidents of malaria declining:</p>
<ul>
<li><p>Insecticide treated bed nets </p></li>
<li><p>effective antimalarial medicines</p></li>
<li><p>indoor residual spraying</p></li>
</ul>
<p>These are the cornerstones of effective malaria control. But there are a few hurdles that threaten their usefulness. These include:</p>
<ul>
<li><p>drug and insecticide resistance</p></li>
<li><p>the quality of antigen based rapid diagnostic malaria test kits. They do not <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-016-1450-z">detect</a> sub-microscopic levels of malaria parasites.</p></li>
</ul>
<p>In addition, malnourished children do not <a href="http://aac.asm.org/content/57/12/5792.full">absorb</a> antimalarial medicines sufficiently to obtain levels in the blood stream that effectively kill the parasites.</p>
<p>It’s clear that more potent interventions are urgently needed. Investment in accelerated development and introduction of vaccines should be prioritised. A <a href="http://www.malariavaccine.org/malaria-and-vaccines/first-generation-vaccine/rtss">malaria vaccine</a> candidate that is currently under trial in Africa, RTSS, has shown a modest 39% efficacy. It has also shown promise with a prediction that in fully immunised children it can avert <a href="https://www.ncbi.nlm.nih.gov/pubmed/26549466">484 deaths per 100,000</a>.</p>
<p>On top of this, more funding needs to be made available as it has a direct impact on the ability of countries to bring malaria under control. For example, in <a href="http://www.cddep.org/tool/malaria_rates_zanzibar_rise_and_fall_funding_levels">Zanzibar</a> the malaria rates rose and fell with funding levels between 1960 and 2013. </p>
<p>Between 1981 and 1983 <a href="http://cgsd.columbia.edu/files/2012/11/STP-Elimination.pdf">Sao Tome</a> reported no malaria cases due to consistent indoor residual spraying of households with DDT twice a year and and weekly administration of drugs to prevent the disease. When the funding dried up, a major epidemic occurred in 1985 and by 1997 malaria prevalence had risen to 53%. </p>
<p>Sao Tome has recovered to the point that it is now in the <a href="http://www.undp.org/content/undp/en/home/presscenter/pressreleases/2016/02/15/end-of-malaria-in-sight-for-s-o-tom-and-pr-ncipe.html">pre-elimination</a> phase. With the current low transmission rates, the end of malaria could be in sight with the annual incidence dropping from 33.8 per 1,000 people in 2009 to 9.7 per 1000 in 2014. </p>
<p>In Kenya, transmission in the <a href="https://bmcinfectdis.biomedcentral.com/articles/10.1186/1471-2334-10-283">highlands of western Kenya</a> was reduced for between 2007 to 2008. This was <a href="https://malariajournal.biomedcentral.com/articles/10.1186/1475-2875-6-72">attributed</a> to widespread indoor residual spraying and the introduction of artemisinin based combination medicines with support from the Global Fund. </p>
<h2>Challenges facing Africa</h2>
<p>Among the key challenges facing Africa in malaria elimination are:</p>
<p><strong>Infrastructure challenges</strong>: weak health systems, resources like manpower, inaccessibility to malaria control services and poor surveillance systems are to blame for a weak roll out during the implementation phase. Health systems are under-resourced and poorly accessible to those most at risk. In 2015, a <a href="http://www.who.int/mediacentre/news/releases/2016/malaria-control-africa/en/">large proportion</a> (36%) of children with a fever were not taken to a health facility for care in 23 African countries. </p>
<p><strong>Drug resistance:</strong> it’s worrying that signs of resistance to artemesinin has been reported in about <a href="https://malariaworld.org/blogs/pierre-lutgen">12</a> African countries. This follows the rapid spread of drug resistance first reported in the greater <a href="https://www.ncbi.nlm.nih.gov/pubmed/24159830">Mekong region</a> in south East Asia. </p>
<p><strong>Insecticide resistance:</strong> since 2010, <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-017-1799-7">60 of the 73</a> countries that monitor insecticide resistance have reported mosquito resistance to at least one insecticide class used in nets and indoor spraying. From these samples, 50 reported resistance to two or more insecticide classes. </p>
<h2>The way forward</h2>
<p>To achieve low transmission rates and eventual elimination, African countries need to invest in understanding the geography, evolutionary history of flora and fauna, infrastructure and land use in Africa. An analysis into the eradication of malaria historically found that by understanding and addressing these factors, malaria control can be <a href="http://www.earth.columbia.edu/sitefiles/file/about/director/pubs/002.pdf">more successful</a>.</p>
<p>In addition, African countries need to diversify financing of malaria control. The initiatives should be cost effective to ensure they are accessible and evenly rolled out even in the continent’s poor resource regions.</p>
<p>And a national health financing strategy and road map to universal health coverage should be developed and implemented in sub-Saharan countries with a high burden of malaria. </p>
<p>All partners from the public and private sector, the civil society, development partners and the community should be involved. One of the reasons that community involvement is important is because it encourages ownership which leads to credible data which in turn makes it possible to monitor progress.</p>
<p>Africa has unfinished business before it achieves the aspirational theme of World Malaria Day – “End Malaria for good”. Robust investment and new malaria control tools are urgently needed to propel countries towards eliminating the disease.</p><img src="https://counter.theconversation.com/content/76526/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Willis Simon Akhwale does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Eliminating malaria in Africa has been held back by a range of factors, including a lack of funds and drug and insecticide resistance challenges.Willis Simon Akhwale, Country Director I-TECH Kenya, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/607992016-06-16T13:08:07Z2016-06-16T13:08:07ZWhy new-fangled mosquito controls should not replace tried and tested methods<figure><img src="https://images.theconversation.com/files/126741/original/image-20160615-14027-1wmpx9s.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">Controlling mosquitoes has a large effect on controlling the diseases they carry.</span> <span class="attribution"><span class="source">Alvin Baez/Reuters</span></span></figcaption></figure><p>In the last 40 years of mosquito-borne viruses such as malaria, yellow fever and dengue, scientists have introduced myriad interventions to control the population of mosquitoes. This is because controlling mosquitoes has a large effect on controlling the diseases since the mosquito is the vector that carries them. </p>
<p>Novel mosquito-control approaches have included everything from deploying sterile male mosquitoes to soaps that could prevent people in high-risk malaria areas from contracting mosquito-borne diseases. </p>
<p>Zika, the latest mosquito-borne virus to be declared a <a href="http://www.portal.pmnch.org/emergencies/zika-virus/articles/one-year-outbreak/en/">global health emergency</a>, has once again propelled innovations to tackle the control of mosquitoes. </p>
<p>There is talk of trying to stop Zika by giving mosquitoes a <a href="http://www.recode.net/2016/5/31/11825676/gates-foundation-chief-code-conference-">sexually transmitted disease</a> and even injecting plants with a bacterium that would alter the <a href="http://www.smithsonianmag.com/science-nature/malaria-zika-and-dengue-could-meet-their-match-mosquito-borne-bacteria-180959271/?no-ist">mosquito’s genome</a> and eliminate its thirst for blood.</p>
<p>Many of these innovations are good ideas but collectively they are only one of the tools in the armament of fighting mosquito-borne diseases. And they should not draw focus away from the tried and tested public health measures to control mosquito-borne diseases. These include environmental sanitation and access to clean water. </p>
<h2>Different innovations</h2>
<p>Making male mosquitoes sterile was one of the first innovations introduced in the 1970s when malaria was considered a problematic disease. This was becase the malaria parasite had become resistant to front line drugs.</p>
<p>Several other quick fixes have also been offered. <a href="http://www.cdc.gov/malaria/malaria_worldwide/reduction/vector_control.html">These</a> include fungi, worms and fish that parasitise and kill larval mosquitoes before they transform into adult mosquitoes. But these innovations were all found to be ineffective.</p>
<p>Changing the genetic makeup of the mosquito has also been explored. It results in mosquitoes that are not susceptible to the parasite. But this approach is still many years from application in field settings. </p>
<p>Having grown up on the banks of a heavily polluted canal in Nigeria and with limited access to potable water, the innovation that most fascinated me is a <a href="http://www.foxnews.com/health/2016/05/12/mosquito-repellent-soap-invention-seeks-to-wash-away-africa-malaria-threat.html">mosquito-repellent soap</a>.</p>
<p>Two African scientists created the soap from natural oils and plants. The hope was that it could successfully prevent mosquito-borne diseases because it is cheap to produce and relies on existing habits such as bathing, cleaning and doing laundry.</p>
<p>But there is a catch. People need access to clean water to use the soap. Given that globally more than 700 million people still lack <a href="http://www.who.int/water_sanitation_health/hygiene/en/">access to safe water</a>, an innovation like a mosquito-repellent soap could become just another quick fix that only serves some but distracts from the complex task of providing more workable solutions.</p>
<p>The use of <a href="http://www.malariaprotection.com/es/wp-content/downloads/research/lindsay.pdf">mosquito-repellent soaps</a> is in fact not a new idea. Natural insect repellents have been in use for millennia and soaps containing such ingredients have been available for at least 30 years.</p>
<p>But natural mosquito-repellent soaps have been shown to have lower efficacy when compared to soaps containing the synthetic repellent DEET. More so, most of those natural ingredients could be <a href="https://malariajournal.biomedcentral.com/articles/10.1186/1475-2875-10-S1-S11">harmful to health</a>. Many of them cause cancer.</p>
<p>Some of these innovations have worked on a small scale but are not as effective on a larger scale. And although the innovations focus on mosquito control, this is only one of many factors that result in the spread of mosquito-borne diseases. </p>
<h2>A complex set of diseases</h2>
<p>The reality is that there are many <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2640300/pdf/9716967.pdf">factors responsible</a> for the persistence and global spread of mosquito-borne diseases. These are complex.</p>
<p>They include: </p>
<ul>
<li><p>insecticide and drug resistance;</p></li>
<li><p>changes in public health policies;</p></li>
<li><p>emphasis on emergency response;</p></li>
<li><p>demographic and societal changes; and </p></li>
<li><p>genetic changes in pathogens. </p></li>
</ul>
<p><a href="http://www.wpro.who.int/mvp/climate_change/about/en/">Climate change</a> is also implicated. Since insects have no internal control over their body temperature, as ambient temperatures rise their distribution may expand through increased reproductive rate, biting behaviour, and survival. </p>
<p>Humidity and the availability of water for breeding in areas that are usually dry also promotes vector distribution and longevity. The incubation period of pathogens in vectors is temperature-dependent and becomes shorter in warmer conditions. </p>
<p>Unprecedented population growth, mostly in developing countries, has resulted in major movements of people, primarily to urban centres. This unplanned and uncontrolled urbanisation has led to inadequate housing and deteriorating water, sewage, and waste-management systems. These produce ideal conditions for mosquito-borne diseases to be transmitted. </p>
<p>My personal experiences and those of the hundreds of patients I treated for recurrent malaria in the slums of southern Nigeria are proof of this.</p>
<h2>The best approach</h2>
<p>So, what is the best way to prevent mosquito-borne diseases? </p>
<p>The variation in malaria’s epidemiology in and between countries shows that a multi-pronged approach is needed. This includes:</p>
<ul>
<li><p>providing and improving public health infrastructure;</p></li>
<li><p>research to develop effective drugs and vaccines; and </p></li>
<li><p>improved vector control using proven techniques while taking up new innovations.</p></li>
</ul>
<p><a href="http://www.sciencedirect.com/science/article/pii/S1473309905702681">Research</a> has shown that mosquito control measures built around environmental management are non- toxic, cost-effective, sustainable and highly effective in reducing morbidity and mortality. Those environmental measures including standing water, vegetation and drainage management all rely on access to clean water and sanitation.</p>
<p>The <a href="http://www.unicef.org/wash/3942_statistics.html">impact</a> of adequate access to clean water, sanitation and hygiene go beyond mosquito control. They are essential for human survival. Access to these basic needs has a positive impact on the overall health, wealth and economic development of people and communities around the world.</p>
<p>Improving access to water also goes a long way in preventing – and even eliminating – other water and sanitation-related diseases such as cholera, <a href="http://www.mayoclinic.org/diseases-conditions/trachoma/basics/definition/con-20025935">trachoma</a>, <a href="http://www.who.int/mediacentre/factsheets/fs115/en/">schistosomiasis</a>, worm infestations and <a href="http://www.who.int/dracunculiasis/disease/en/">guinea worm disease</a>. </p>
<p>UNICEF <a href="http://www.unicef.org/wash/3942_statistics.html">estimates</a> that if countries in need were able to get basic, low-cost water and sanitation facilities, the world would save around US$263 billion a year. Those savings would come from obviated health and labour expenses. </p>
<p>The threats that mosquito-borne diseases pose to global health are as real as the are complex. The response must be broad and calculated. It must apply proven interventions while trying out new ideas. </p>
<p>Public health innovations should be considered as just one tool in our armament. They should not distract us, as they sometimes have, from the complex task of protecting and promoting global health through interventions like improving access to clean water, sanitation and hygiene.</p><img src="https://counter.theconversation.com/content/60799/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Utibe Effiong does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Innovations targeted at mosquito control are good but should not draw focus away from the tried and tested public health measures to control mosquito-borne diseases.Utibe Effiong, Resident Physician at St Mary Mercy Hospital and Research Scientist for the Exposure Research Laboratory, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/511712015-11-26T14:01:09Z2015-11-26T14:01:09ZExplainer: what is a gene drive and how could it wipe out malaria?<figure><img src="https://images.theconversation.com/files/103345/original/image-20151126-28268-14pvpdi.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Our understanding of the natural world is now so great we can manipulate the DNA blueprints for any living thing on Earth. We can replace genes for traits we don’t like with others we prefer and even add genes that don’t occur naturally in an organism. Over the last few years, scientists have developed several methods for editing genes in this way and excitement over one in particular, the CRISPR-Cas9 system, has reached fever pitch. </p>
<p>We have also developed a way to introduce these gene changes to an entire population of a species. This “gene drive” process has most recently <a href="http://www.bbc.co.uk/news/health-34898931">been used</a> to alter the DNA of small groups of mosquitoes so that they no longer carry the malaria parasite, raising the possibility of eliminating the disease altogether. But meddling with nature in this way carries huge implications that need careful consideration.</p>
<h2>Gene editing</h2>
<p>Gene-editing techniques involving cutting genes at specific sites in the DNA of an embryo in order to disrupt those genes’ function or insert other genes. For instance, <a href="https://theconversation.com/explainer-crispr-technology-brings-precise-genetic-editing-and-raises-ethical-questions-39219">the CRISPR-Cas9 system</a> uses enzymes that can cut specific gene sequences from DNA, guided by a similar molecule known as RNA. Natural gene repair mechanisms then kick in and can be used to disrupt the function of the original gene or replace it with a completely different one.</p>
<p>CRISPR systems actually aren’t new – they have existed in nature for millions of years. Bacteria use them to fend off viral infections by adding part of the virus’s DNA to their own. So why all the fuss? CRISPR-Cas9 makes artifical gene-editing much easier and cheaper, enabling scientist to target specific bits of DNA. By comparison, another method known as TALENS requires the construction of complex proteins. As a result, CRISPR gene-editing is heralding advances in biomedicine such as <a href="http://www.statnews.com/2015/11/05/doctors-report-first-use-gene-editing-technology-patient/">cancer treatments</a> and protecting individuals <a href="http://www.independent.co.uk/news/science/crispr-breakthrough-announced-in-technique-of-editing-dna-to-fight-off-deadly-illnesses-10420050.html">from infections</a></p>
<p>But there are other ways gene-editing has the potential to help in the fight against infectious diseases. <a href="http://www.nature.com/news/gene-drive-mosquitoes-engineered-to-fight-malaria-1.18858">Very recently</a>, CRISPR methods have been used to make mosquitoes resistant to malaria infections and coupled with a “chain reaction” to drive this gene modification (the resistance to malaria parasite) through the population.</p>
<h2>Gene drive</h2>
<p>This process is referred to as a “gene drive”, and again is not new: nature spreads evolutionary changes through a population all the time. It doesn’t mean changing the DNA of all living individuals in a population. Instead it’s about ensuring a specific genotype (a certain version of a gene) is passed on to the descendants of modified individuals.</p>
<p>A sexually reproducing organism usually has a 50% chance of inheriting a specific genotype from one of its parents. Using a gene drive can bias the inheritance pattern to increase that chance to nearly 100%, ensuring almost all descendants possess the genotype. As those descendants mate and produce their own offspring, the proportion of organisms with the genotype increases until it can be found in the entire population.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/103346/original/image-20151126-28284-7ks03l.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/103346/original/image-20151126-28284-7ks03l.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/103346/original/image-20151126-28284-7ks03l.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/103346/original/image-20151126-28284-7ks03l.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/103346/original/image-20151126-28284-7ks03l.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/103346/original/image-20151126-28284-7ks03l.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/103346/original/image-20151126-28284-7ks03l.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Gene warfare on malaria.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>The idea that you can “replace” a population’s genotype is particularly appealing when that population is responsible for spreading disease, as mosquitoes are with malaria. Malaria is preventable and curable but still kills over <a href="http://www.who.int/mediacentre/factsheets/fs094/en/">400,000 people each year</a>.</p>
<p>The potential for using a gene drive to engineer insects (particularly mosquitoes) was discovered <a href="http://www.nature.com/nature/journal/v218/n5139/abs/218368a0.html">in the 1960s</a>. But the advent of CRISPR’s cheap and easy gene-editing puts this research onto a whole new footing. Researchers at the University of California, Irvine, <a href="http://www.pnas.org/content/early/2015/11/18/1521077112.abstract">recently published</a> a proof-of-princple study demonstrating the techniques can alter a population of the main type of mosquito that carries malaria in urban India, <em>Anopheles stephensi</em>.</p>
<h2>Putting into practice</h2>
<p>The longer term aim, in this instance, might be to release a persistent, modified mosquito into the environment to assist in the control a public health problem. This would be an area-wide release programme to compliment existing control interventions that would require case-by-case assessment of all the cost and benefits. For example, mathematical modelling would be needed to work out how many modified mosquitoes to release, how long it would take for the mosquito population to be clearly affected and how long it would take to impact public health.</p>
<p>One obstacle to the practical use of gene-drives is the need for relevant regulations, or at least the application of existing laws on genetic modifications. Gene-drive technologies are still some way off from the necessary environmental risk assessments for field trials and releases that would sufficiently scrutinise the risks to the environment and/or human health. These sorts of CRISPR-based modifications might even need a whole new set of regulatory structures that require a fuller debate about novel biotechnological advances.</p>
<p>Rapidly targeting genome modifications has the power to advance many aspects of basic and translational biomedical sciences. The potential benefits to reducing the impact of infectious disease and genetic disorders, including cancers, and improving the way the immune system works are huge. But the technology isn’t without pitfalls.</p>
<p>CRISPR systems rely on a guide molecule to make sure the DNA sequence is cut in exactly the right place. Getting this wrong will probably cause damage to non-target genes that could harm the organism. And just because we can edit the DNA within a species doesn’t mean we should. We need strong leadership at all levels – ethical, scientific, political – and appropriate regulations to ensure these new technologies can prosper without unintended consequences.</p><img src="https://counter.theconversation.com/content/51171/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Bonsall receives funding from BBSRC. </span></em></p>New genetic technology could change the DNA of entire species to prevent them from spreading diseases.Michael Bonsall, Professor of Mathematical Biology, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/498732015-11-04T04:05:01Z2015-11-04T04:05:01ZSeven things worth knowing about mosquitoes<figure><img src="https://images.theconversation.com/files/100535/original/image-20151102-16527-1dthulh.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">Anopheles Gambiae, one of three mosquitoes found in Africa that transmit malaria.</span> <span class="attribution"><span class="source">shutterstock</span></span></figcaption></figure><p><em><em>This article is part of a series The Conversation Africa is running as part of the South African Development Community malaria week. You can read the rest of the series <a href="https://theconversation.com/africa/topics/sadc-malaria-week">here</a>.</em></em></p>
<p><strong>1. Not all mosquitoes bite.</strong></p>
<p>The female mosquitoes are the dangerous ones. They bite and draw blood. Male mosquitoes feed on flower nectar. Males have very hairy and fuzzy antennae (like a powder puff) whereas females have less hairy antennae. </p>
<p><strong>2. There are three types of malaria carrying mosquitoes.</strong></p>
<p>The top three malaria transmitters in Africa are Anopheles gambiae, Anopheles funestus and Anopheles arabiensis. The first two live in areas of Africa where there is higher rainfall while the third, Anopheles arabiensis, is a more savanna-based, arid zone species. </p>
<p>Gambiae and funestus prefer to feed indoors and are strongly attracted to humans, but arabiensis feeds as easily outdoors as indoors and also as easily on cattle and other animals as humans. This means it is easier to target gambiae and funestus using indoor methods such as spraying walls with insecticides and using insecticide-impregnated bed nets. The outdoor-feeding arabiensis is far more difficult to control. </p>
<p>In most areas all three species have a peak of biting in the early hours of the morning when people are in their deepest sleep and less likely to disturb mosquitoes during the feeding process. There are also other important species of malaria-transmitting mosquitoes but they are more localised in distribution.</p>
<p><strong>3. Mosquitoes have started to change their feeding patterns.</strong></p>
<p>Because of the strong focus on indoor strategies to fight malaria transmitting mosquitoes using bed nets and indoor spraying, genetic selection is resulting in some populations of these mosquitoes biting outdoors and earlier at night when people are not protected by bed nets. It means these mosquitoes are more difficult to reach with insecticides, just as is the case with Anopheles arabiensis.</p>
<p><strong>4. Most mosquito bites are harmless. It’s only the ones that carry certain types of parasites that lead to malaria, and potentially death.</strong></p>
<p>In Africa, there are four known species of microscopically small parasites that can cause the disease we call malaria. All four belong to the group <em>Plasmodium</em>. The most common of these parasites in Africa is <em>Plasmodium falciparum</em>, which is the most deadly of the four species. </p>
<p>Birds and some other groups of animals carry their own species of <em>Plasmodium</em>, which is also transmitted by mosquitoes, but they do not cause malaria in humans. Mosquitoes also carry many other disease-causing organisms such as yellow fever virus, West Nile virus, Rift Valley fever, and the worms that cause the dreaded disfiguring elephantiasis (filariasis).</p>
<p><strong>5. Mosquitoes select where they feed on the body. They have very acute sensory mechanisms (like heat-seeking missiles) that lead them to select particular parts of the body (such as ankles) to feed from.</strong></p>
<p>All three of the main malaria carrying mosquitoes have similar biting preferences. If you are sitting or standing outside in the evening the overwhelming majority will try to feed on your ankles and feet - so make sure you cover these areas with repellent or wear socks and shoes.</p>
<p>The antennae of mosquitoes are highly specialised sensory organs that can detect very small amounts of chemical cues that lead them to food and mates. Various chemicals, of which carbon dioxide is one, help female mosquitoes track down their hosts. Pheromones, which are hormones secreted as odours into the environment, enable males and females to meet and mate. They are also detected by the antennae.</p>
<p><strong>6. Malaria mosquitoes do not like wind.</strong></p>
<p>Using a fan over you when going to bed will lessen your chances of being bitten. These mosquitoes don’t like flying when there is even a slight breeze.</p>
<p><strong>7. 97 countries and territories still face ongoing malaria transmission.</strong></p>
<p>According to the World Health Organisation, an estimated 3.2 billion people, or just under half the world’s population, are at risk of getting malaria. The bulk of the malaria burden is shouldered by Africa where 89% of cases and 91% of deaths occur.</p><img src="https://counter.theconversation.com/content/49873/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Professor Leo Braack received funding from Bill &amp; Melinda Gates Foundation and also University of Pretoria to conduct malaria research</span></em></p>The irritating buzz that rings in your ear in the dead of the night comes from an insect barely traceable with your naked eye. Here are a few facts worth knowing about the mosquito.Leo Braack, Research Chair, Integrated Vector Management in the Vector Control Cluster, Centre for Sustainable Malaria Control , University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/499862015-11-03T04:06:11Z2015-11-03T04:06:11ZThe quest to find a drug that nails the tricky malaria parasite<figure><img src="https://images.theconversation.com/files/100525/original/image-20151102-16554-rjrqi5.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">A doctor observes mosquitoes to better understand the malaria parasite which has been developing a resistance to the anti-malarial drugs.</span> <span class="attribution"><span class="source">Reuters/RIcardo Rojas</span></span></figcaption></figure><p><em><em>This article is part of a series The Conversation Africa is running during malaria week in the Southern African Development Community. You can read the rest of the series <a href="https://theconversation.com/africa/topics/sadc-malaria-week">here</a>.</em></em></p>
<p>Malaria is a killer that has spent thousands of years adapting to the habits of its victim. Although the first confirmed case of human malaria dates to 450 AD, a millennia and a half later, the world is still battling the parasite that causes this disease. Today at least <a href="http://www.who.int/malaria/media/world_malaria_report_2014/en/">3.3 billion</a> people, or almost half of the world’s population, are at risk of contracting malaria. The heaviest burden is in Africa where an estimated 90% of malaria deaths occur.</p>
<p>To eliminate malaria and alleviate the disease scientists have to develop drugs that kill the parasite in the blood. But to prevent the spread of the disease in a community, these drugs also have to kill transmissible versions of the parasite that develop. </p>
<p>The challenge is that the world is running out of usable antimalarial <a href="http://www.who.int/malaria/media/world_malaria_report_2014/en/">drugs</a>. Antimalarial drugs that are widely used have a limited usable lifespan. This is because parasites develop resistance. The current drugs are becoming less effective as the parasite develops resistance against them. </p>
<p>To tackle this problem, researchers are investigating potential antimalarial drugs with multiple <a href="http://www.biomedcentral.com/content/pdf/s12936-015-0572-z.pdf">targets</a> to overwhelm the parasite and reduce resistance development. Multi-target drugs may also speed up the drug discovery and development process.</p>
<p>The multi-target inhibitors that we are <a href="http://www.biomedcentral.com/content/pdf/s12936-015-0572-z.pdf">studying</a> have been shown to target both the disease causing and transmissible forms.</p>
<h2>Understanding the malaria parasite</h2>
<p>The malaria parasite is an amazing shape shifter. It is able to change its shape in different environments to cause and spread the disease. In infected humans, the parasite lives within red blood cells leading to the symptoms and complications of the disease. The main symptoms include fever, headaches and vomiting which usually appear between 10 and 15 days after the mosquito <a href="http://www.who.int/topics/malaria/en/">bite</a>.</p>
<p>But when a female mosquito bites a human infected with malaria, a special form of the parasite, called a gametocyte, is drawn up from the person along with their blood. This special parasite then develops further in the newly infected mosquito and matures into another form of parasite that can be transferred to another human when the mosquito bites someone else. This leads to the spread of malaria. </p>
<p>With repeated exposure to a drug, the parasite cleverly adapts to the presence of the drug by changing its DNA. This means that the drug target in the parasite is no longer affected by the drug or that the parasite gets rid of the drug before it can reach its target. </p>
<p>To slow down the ability of the parasite to develop drug resistance, malaria medicine has been formulated into a combination therapy. It combines two antimalarial drugs that target different biological processes in a single tablet. It is considerably more difficult for the parasite to simultaneously change both targets in order to become resistant against both drugs. With combination therapies, the parasite has a significantly reduced chance of developing resistance compared to a single therapy. </p>
<p>Even though combination therapies have assisted in slowing down parasite drug resistance, the parasite is developing drug resistance to an antimalarial drug faster than new drugs are being developed and approved. </p>
<h2>A multi-pronged approach</h2>
<p>To increase and sustain the antimalarial armoury, drug developers need to deliver drugs faster and increase the lifespan of the drugs that are in circulation. </p>
<p>The answer to this conundrum may lie in the field of antibiotic drug discovery. </p>
<p>The antibiotic field is currently developing resistance-resistant <a href="http://www.cell.com/trends/pharmacological-sciences/abstract/S0165-6147(14)00172-2">antibiotics</a> that have multiple targets instead of single targets. Instead of a combination therapy that targets two single targets, a multi-target drug has numerous targets which the parasites need to develop resistance against. This makes it exponentially more effective than a combination therapy in resisting resistance. </p>
<p>One example of the outstanding success of this strategy is the TB drug, <a href="http://openres.ersjournals.com/content/1/1/00010-2015.full">SQ109</a>, which is currently in phase II clinical trials. It inhibits multiple targets with potent inhibition of TB cell growth and very low rates of spontaneous drug resistance. </p>
<p>A multi-target drug approach may provide the desired drug discovery breakthrough required to treat malaria. It would speed up the delivery of candidates into clinical practice and decrease drug resistance. </p>
<p>Ultimately, it would stop the spread of malaria by targeting the transmissible forms. In this way, we hope to stay one step ahead of the malaria parasite and make a dramatic difference to curb and eliminate the disease.</p><img src="https://counter.theconversation.com/content/49986/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bianca Verlinden receives funding from the SA National Research Foundation and SA Medical Research Council. </span></em></p><p class="fine-print"><em><span>Lyn-Marie Birkholtz receives research funding from the SA National Research Foundation and the SA Medical Research Council. </span></em></p>Across the world scientists are trying to find a new drug that the malaria carrying parasite will struggle to develop a resistance to.Bianca Verlinden, Postdoctoral Research Fellow, Molecular Parasitology, Department of Biochemistry, University of PretoriaLyn-Marie Birkholtz, Associate Professor (Biochemistry) DST/NRF South African Research Chair (SARChI) in Sustainable Malaria Control, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/498482015-11-01T11:07:52Z2015-11-01T11:07:52ZParts of southern Africa are within tantalising reach of eliminating malaria<figure><img src="https://images.theconversation.com/files/100338/original/image-20151030-16554-1qj7h1i.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">A young girl plays inside a mosquito net in Kibera, Nairobi. </span> <span class="attribution"><span class="source">EPA/Stephen Morrison</span></span></figcaption></figure><p><em><em>This article is part of a series The Conversation Africa is running as part of the SADC malaria week. You can read the rest of the series <a href="https://theconversation.com/africa/topics/sadc-malaria-week">here</a>.</em></em></p>
<p>There has been a concerted international effort since the early 2000s to tackle malaria. This has led to dramatic reductions in the disease. </p>
<p>World Health Organisation estimates show that in 2015 there were <a href="http://www.who.int/malaria/media/malaria-mdg-target/en/">214 million</a> malaria cases and 438,000 deaths globally. This is a 37% decrease in the incidence rate of malaria compared to 15 years ago and a 60% reduction in deaths.</p>
<p>Most of the gains have happened in Asia and “fringe” areas in Africa, which is at the periphery of distribution of the disease. But the challenge is that sub-Saharan Africa still shoulders 89% of existing cases and 91% of deaths from the disease. </p>
<h2>How successes have been achieved</h2>
<p>Africa has historically had a high transmission rate. Southern Africa has been particularly successful in reducing its case load. The Seychelles and Mauritius have completely eliminated malaria. They have had no new local transmissions in recent years – only some imported cases that were locally diagnosed and treated.</p>
<p>In South Africa there was an exceptional peak of <a href="http://www.scielo.org.za/scielo.php?pid=S0256-95742013001000029&amp;script=sci_arttext&amp;tlng=es">64,622 cases</a> in 2000. Since then case numbers have dwindled to between 6000 and 10,000 in recent years. </p>
<p>This reflects reductions in several of South Africa’s neighbouring countries such as Botswana, Namibia, and Swaziland – where malaria mortality rates are close to zero. </p>
<p>These four countries are in the pre-elimination and elimination stages. Malaria incidence in all of them makes up less than five cases per thousand people. This means they are within sight of eliminating malaria – a tantalising target that South Africa hopes to reach <a href="http://www.scielo.org.za/scielo.php?pid=S0256-95742013001000035&amp;script=sci_arttext&amp;tlng=en">by 2018</a>.</p>
<p>But that reward is proving hard to achieve despite the dedicated efforts by the national malaria control programs in each country. </p>
<h2>The reasons why full elimination is so difficult</h2>
<p>The standard tools used almost universally for malaria control are: </p>
<ul>
<li><p>providing households with insecticide-treated bednets (ITNs);</p></li>
<li><p>indoor residual spraying (IRS) of insecticides against mosquitoes that enter households; and</p></li>
<li><p>dedicated efforts to detect malaria cases and treat them with effective anti-malarial drugs. </p></li>
</ul>
<p>When these three tools are used in combination, they have resulted in the reversal and decline in malaria cases almost globally. But what was once an effective approach to harvest the low-hanging fruit to achieve relatively quick success have now become blunt tools. </p>
<p>The interventions now lack the surgical precision to clear up what is known as “residual malaria”. These are the portion of cases that pop up for reasons that are not always known and do not yield to persistent use of the traditional tools.</p>
<p>A major contributing factor, especially in the case of South Africa, is the large numbers of migrants and visitors from high-transmission malaria countries further north. Although Gauteng, South Africa’s economic hub, was never a problem province, it now has the highest number of cases in the country.</p>
<p>The cases are through infected people entering the country and becoming ill once they have arrived, or vehicles returning from high-transmission countries with malaria-infected mosquitoes hitching a ride.</p>
<p>There are other reasons too. </p>
<p>Some countries do not have a policies to deal effectively with the particular life stages that infect mosquitoes. Malaria parasites have a complex life cycle involving different forms having different target organs and functions. Only one stage – the sexual gametocytes – are able to infect mosquitoes that leads to infecting other people. </p>
<p>Although doctors prescribe medication that kills the numerous asexual parasites in the blood which then cures infected people of the malaria symptoms, it does not effectively inactivate the sexual gametocytes that infect mosquitoes, at least in Africa where the deadliest species of malaria parasite is most common.</p>
<p>There are also chronic systemic challenges. These include a shortage of manpower, funding, lost skills that are not replaced, and a mindset still geared to the decades-long traditional approach to combat malaria. </p>
<h2>New frontier</h2>
<p>Entering the elimination stage is a relatively new frontier for the southern African countries. </p>
<p>There are more hazy possibilities that come into play with residual malaria. This includes the unknown role of secondary vectors. Traditional malaria control tools have targeted a very limited set of mainly <a href="http://www.parasitesandvectors.com/content/3/1/72">three mosquito species</a> with known behaviour. </p>
<p>Addressing these three species has resulted in successes. But with residual malaria we may be dealing with unknown secondary vector mosquitoes that previously played a minor role but now keep the disease ticking over.</p>
<p>Also, across the world there are increasing numbers of countries where mosquito populations are building resistance to available insecticides used for spraying. What is more concerning is that malaria parasites are also developing resistance to the only, and best, available anti-malarial compound, artemisinin.</p>
<p>This resistance is currently still confined to geographic pockets in southeast Asia, but precedents exist where such resistance rapidly spreads to other parts of the globe.</p>
<p>Another concern is loss of political will to continue the high financial and other demands associated with effective malaria programs – and donor fatigue. </p>
<p>Most of the money being poured into malaria control at global scale comes from international donors. Once again precedent has shown that in the face of diminishing returns such donors lose commitment.</p>
<h2>The last lap</h2>
<p>Botswana, Namibia, South Africa and Swaziland – unlike many other African countries confronted with particular economic and political challenges – are very likely to achieve zero local transmission. </p>
<p>The lessons learnt in South Africa and its neighbours is of great importance. There is some urgency in cementing these successes. </p>
<p>But then the real challenge will emerge: the will of national governments to continue funding a program that has achieved its goal. The moment it weakens its defences, malaria is likely to rebound extremely quickly in the face of migration and importation from high-transmission neighbouring countries that are still fighting to bring malaria under control.</p><img src="https://counter.theconversation.com/content/49848/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Professor Leo Braack received funding from Bill and Melinda Gates Foundation and University of Pretoria for research on malaria.</span></em></p>Several countries within southern Africa are on the brink of eliminating malaria. But there are several challenges ahead.Leo Braack, Research Chair, Integrated Vector Management in the Vector Control cluster at the Centre for Sustainable Malaria Control , University of PretoriaLicensed as Creative Commons – attribution, no derivatives.